Controlling tilt of a survey instrument is a major activity for a surveyor. A great deal of time and effort is devoted to insuring that a survey instrument is leveled. Conventional methods of leveling a survey instrument involve aligning the survey instrument with a local gravity vector using a bubble level. Typical survey procedures involve leveling a survey instrument before performing measurements so that data is nearly free of tilt errors.
Today's survey instruments often comprise an optical system and a Global Navigation Satellite System (GNSS), otherwise referred to a Global Positioning System (GPS). A conventional GNSS survey instrument typically includes a location measurement device coupled to an end of a surveyor's pole, whereas a conventional optical survey instrument (e.g., optical total station) typically uses a tripod support system. The GNSS type of survey instrument is used to determine locations of points of interest that are typically located on the ground when many data points are desired, owing to its ease of portability. A bottom or tip of the surveyor's pole is placed at the point of interest, held in a vertical position as indicated by the bubble level, and a location measurement is obtained. Leveling ensures that a measurement center (e.g., the antenna phase center) of the location measurement device is as close to directly above the point of interest as possible. This is important because error is introduced if the measurement center is not directly above the point of interest. For example, a surveyor's pole that is two-meters long and is tilted two degrees from vertical can result in as much as two centimeters of measurement error. That is, the measurement center of the location measurement device may be as much as two centimeters to one side of the point of interest.
If the time required to level a survey instrument could be reduced or eliminated, a surveyor could be more productive by taking more measurements during a given time period. Thus, improved methods and instruments are continually desired to reduce the time and effort required to level a survey instrument. This applies to GNSS survey instruments, optical survey instruments, handheld survey instruments, and any other type of survey instrument that utilizes leveling processes.